JP2003152147A - Heat conductive composite, heat conductive pressure sensitive adhesive sheet as well as jointing structure of heat generating body and heat dissipation body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat conductive composite having excellent adhesiveness and adhesion properties while having so excellent heat conductivity that thermal convection remarkably deteriorating a heat conductivity, even at a temperature within the operating temperature range of a heat generating body is not generated, a heat conductive heat sensitive adhesive sheet consisting of the heat conductive composite as well as a jointing structure of the heat generating body, and a heat dissipating body which employs a heat conductive heat sensitive adhesive sheet consisting of the heat conductive composite. SOLUTION: In the heat conductive composite consisting of two kinds or more of compounds and used while interposing the same between the heat generating body and the heat dissipating body, the compounds of two kinds or more are under a mixed condition that they will not be spontaneously separated at a temperature lower than that in the operating temperature range of the heat generating body, while the phases of the same are separated into a phase, oozing at a temperature within the operating temperature range of the heat generating body, and another phase, not oozing at the same temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent adhesion and adhesiveness, and has excellent heat resistance without causing heat convection that significantly deteriorates thermal conductivity even at a temperature within the operating temperature range of a heating element. The present invention relates to a heat-conductive composition having conductivity, a heat-conductive pressure-sensitive adhesive sheet made of the heat-conductive composition, and a joint structure between a heat-generating body and a heat-dissipating body using the heat-conductive composition.

[0002]

2. Description of the Related Art Conventionally, an adhesive sheet using a heat-conductive pressure-sensitive adhesive (hereinafter also referred to as a heat-conductive pressure-sensitive adhesive sheet) is used to dissipate heat generated by a heating element such as an electric / electronic component. It is used by being interposed between a heating element and a radiator. However, the surfaces of the heat generating element and the heat radiating element are often not smooth, and the heat-conductive pressure-sensitive adhesive sheet cannot be adhered to each other and a sufficient contact area cannot be obtained in many cases. For this reason,
Even if a heat-conductive pressure-sensitive adhesive sheet is used between the heating element and the heat-dissipating element, there is a problem in that the heat-conducting efficiency is poor and a sufficient heat-dissipating effect cannot be obtained. It was necessary to improve the adhesion of the pressure-bonded sheet to the heat generating element and the heat radiating element.

As a technique for improving the adhesion to the heating element and the radiator, US Pat. No. 5,950,
No. 066 describes a heat conductive composition obtained by adding heat conductive fine particles to a resin having a melting point of about 30 to 90 ° C. This is because the heat from the heating element melts the resin to improve the adhesiveness with the heating element and the radiator, and the temperature and pressure compress the thickness of the thermally conductive composition to achieve high heat radiation. It is the one that seeks the effect. However, since this heat conductive composition contains a large amount of olefin wax and the like, its adhesive strength is extremely weak, and there is a problem in that it is extremely difficult to adhere to the heating element and the like.

Similarly, US Pat. No. 6,054,198
The specification also discloses a heat conductive composition in which a resin is melted by heat from a heating element. However, since this heat conductive composition becomes a liquid due to the heat from the heating element during the operation of the heating element, heat convection occurs and the thermal conductivity is significantly deteriorated, and in principle, it can be used for heat dissipation of electronic parts and the like. There was a problem that I could not.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present invention has excellent adhesion and adhesiveness, and has a heat convection that significantly deteriorates the thermal conductivity even at a temperature within the operating temperature range of the heating element. Thermally conductive composition having excellent thermal conductivity without generation, thermally conductive pressure-sensitive adhesive sheet made of the thermally conductive composition, and joint structure between a heating element and a radiator using the thermally conductive composition The purpose is to provide.

[0006]

The present invention is a thermally conductive composition comprising two or more kinds of compounds, which is used by being interposed between a heat generating body and a heat radiating body. The compound is in a mixed state in which it does not spontaneously separate at a temperature lower than the operating temperature range of the heating element, and phase-separates into one that leaks and one that does not leak at a temperature within the operating temperature range of the heating element. It is a heat conductive composition. The present invention is described in detail below.

The heat conductive composition of the present invention is composed of two or more kinds of compounds and is used by being interposed between a heat generating element and a heat radiating element. The two or more compounds are in a mixed state that does not spontaneously separate at a temperature lower than the operating temperature range of the heating element. That is, at the above-mentioned temperature, the above-mentioned two or more compounds are slowly bonded by interactions such as hydrogen bond, interaction between aromatic rings, electrostatic interaction between acid-alkali or cation-anion, and spontaneous reaction. It is in a mixed state that does not physically separate. Therefore, at a relatively low temperature such as room temperature, there is no change in composition due to evaporation or bleeding of a specific component, and the composition is in a solid state, so management and handling are easy. The two or more compounds preferably have a binding site that contributes to the interaction.

Examples of the heating element include electric / electronic parts. The operating temperature range of the heating element is a temperature range indicated by the heating element in the operating state, and the upper limit thereof is, for example, when the heating element is an electric / electronic component, the electric / electronic It is the junction temperature of parts. On the other hand, the lower limit of the operating temperature range of the heating element is the minimum temperature at which heat dissipation is required and is at least higher than room temperature. The junction temperature is generally 100 ° C. or lower, though it varies depending on the type of electric / electronic parts that are heating elements. As the heat radiator,
Examples thereof include heat dissipation components such as heat sinks and heat pipes, electrical cooling devices such as Peltier elements, and cooling devices that circulate a cooling medium such as cooling water.

The above two or more compounds are phase-separated into those that leak and those that do not leak at a temperature within the operating temperature range of the heating element. That is, the thermally conductive composition of the present invention comprises a compound that partially or wholly leaks from the thermally conductive composition of the present invention at the above temperature and a compound that does not leak, and the leaking compound is a heating element and a heat radiator. It does not impair the excellent adhesion and adhesiveness to the heating element and radiator by adhering to the unevenness of the surface, and the above-mentioned non-leakable compound does not melt so that the generation of thermal convection is suppressed and excellent thermal conductivity is obtained. be able to. In addition, the thermally conductive composition is compressed and positively leaks, whereby the distance between the heat generating element and the heat radiating element is shortened, and the heat conductivity can be further improved.

The combination of such compounds is not particularly limited, but, for example, at a temperature lower than the operating temperature range of the heating element, they are in a mixed state in which they do not spontaneously separate.
A compound that is a solid or semi-solid at a temperature within the operating temperature range of the heating element (hereinafter, also referred to as a non-molten compound) and a compound that is in a liquid state at a temperature within the operating temperature range of the heating element (hereinafter also referred to as a molten compound) The combination with is preferred.
In the present invention, the solid means a material that does not exhibit fluidity even when subjected to an external force, and the semi-solid means that the material does not exhibit fluidity when subjected to an external force and receives a strong external force. It means that the liquid exhibits fluidity for the first time, and the liquid may have a low viscosity or a high viscosity, but at least it shows a fluidity without receiving a strong external force. is there. Further, the liquid has a fluidity higher than that of at least the semi-solid. As the non-melting compound and the melting compound, those which do not spontaneously separate in a mixed state at a temperature below the operating temperature range of the heating element may be used, and basically, a combination having poor compatibility is selected. It is preferable. The non-melting compound and the melting compound may be contained in one kind or two or more kinds, respectively.

The non-melting compound is not particularly limited, and examples thereof include acrylic resin, polyester resin, methacrylic resin, olefin resin, urethane resin,
Epoxy resin, vinyl acetate resin, styrene resin,
Examples thereof include butyral-based resins, poval-based resins and silicone-based resins, and modified products thereof. Preferred is an adhesive resin, for example, an acrylic resin,
Examples include polyester resins.

The molten compound is not particularly limited,
For example, when benzyl methacrylate is used as the non-melting compound and the interaction between aromatic rings is used to form a mixed state at a temperature lower than the operating temperature range of the heating element, it is a compound having a benzene ring. Dioctyl phthalate, lauryl benzene and the like can be selected, and dimethylaminoethyl methacrylate is used as a non-melting compound to form an acid-alkali electrostatic interaction to form a mixed state at a temperature lower than the operating temperature range of the heating element. In the case of utilizing for the above, octanoic acid, isostearic acid and the like can be selected. The molten compound is preferably used in an amount of 50% by weight or more based on the total amount of the heat conductive composition of the present invention. When it is less than 50% by weight, the adhesion and the adhesive force to the heat radiator and the heat generator may be insufficient.

The heat conductive composition of the present invention preferably contains heat conductive fine particles in order to improve the heat conductivity. Examples of the heat conductive fine particles include ceramic heat conductive fine particles of boron nitride, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, zinc oxide, and the like; metal powders of aluminum, copper, silver, and the like. . Among them, boron nitride, silicon carbide, aluminum nitride, aluminum, copper and silver are preferable because they have high thermal conductivity and can impart high thermal conductivity to the thermally conductive composition of the present invention with a small filling amount.

The purity of the heat conductive fine particles is preferably 95% by weight or more. If it is less than 95% by weight, the thermal conductivity is lowered, and the amount added must be increased to compensate for it, and the flexibility and shape retention of the thermally conductive composition are impaired. More preferably, it is 97% by weight or more.

The average particle diameter of the heat conductive fine particles is 10
It is preferably 0 μm or less. When it exceeds 100 μm, the surface smoothness of the obtained heat conductive pressure-sensitive adhesive sheet becomes low,
It is difficult to get close contact with the heating element and radiator, and it is difficult to obtain high thermal conductivity. More preferably, the lower limit is 0.5 μm and the upper limit is 50 μm.
μm.

The addition amount of the heat conductive fine particles is preferably 10 parts by weight and 500 parts by weight with respect to 100 parts by weight of the total amount of the non-melting compound and the melting compound. If it is less than 10 parts by weight, it is difficult to obtain high thermal conductivity, and if it exceeds 500 parts by weight, the strength of the thermally conductive composition of the present invention is greatly reduced, and flexibility and shape retention are impaired. is there. A more preferred lower limit is 15 parts by weight and a more preferred upper limit is 400 parts by weight.

The heat conductive composition of the present invention may contain a tackifying resin in order to improve the adhesiveness between the heat generating element and the heat radiating element. By containing the tackifying resin, the adhesiveness, particularly the adhesiveness with metal can be improved. Examples of the tackifying resin include α-pinene polymer, β-pinene polymer, dipentene polymer, terpene-phenol, poly-terpene resin such as α-pinene-phenol copolymer, Escoretz (above, manufactured by Esso Chemical Co., Ltd.), tacky roll. (Sumitomo Chemical Co., Ltd.), Tac Ace (Mitsui Petrochemical Co., Ltd.), etc. C5
Petroleum resin: C9 petroleum resin such as petrozine (manufactured by Mitsui Petrochemical Co., Ltd.), Hiresin (manufactured by Toho Chemical Co., Ltd.), Alcon (manufactured by Arakawa Chemical Co., Ltd.); rosin, modified rosin, polymerized rosin, rosin ester, partially hydrogenated rosin Examples include rosin-based resins such as completely hydrogenated rosin; DCPC-based petroleum resins, styrene-based resins, alkylphenol-based resins, polybutene, polyisobutylene, and the like. In addition, by containing an acid-modified version of these tackifying resins, the adhesiveness with metals can be further improved. These may be used alone or in combination of two or more. Further, the compounding amount of the tackifying resin is preferably 3 parts by weight and 50 parts by weight with respect to 100 parts by weight of the total amount of the non-melting compound and the melting compound. If it is less than 3 parts by weight, the effect of improving the adhesiveness is hardly obtained, and if it exceeds 50 parts by weight, the flexibility of the resin is impaired and the fluidity and the thermal conductivity may be adversely affected. A more preferred lower limit is 5 parts by weight and a more preferred upper limit is 40 parts by weight.

The heat conductive composition of the present invention comprises a filler, a thickener, a pigment,
You may further contain additives, such as antioxidant.

A heat conductive pressure sensitive adhesive sheet comprising the heat conductive composition of the present invention is also one of the present invention. The heat conductive composition of the present invention can be processed into a sheet or tape having a heat conductive pressure sensitive adhesive layer by being formed into a sheet. The method for producing the sheet or tape is not particularly limited, and examples thereof include solvent casting method and U
V polymerization method, sheet molding method such as hot melt coating and the like can be mentioned. Examples of the method for obtaining the thermally conductive pressure-sensitive adhesive sheet of the present invention include the following methods. A mixture is prepared by dispersing or dissolving a non-melting compound, a melting compound, heat conductive fine particles, the above tackifier and other additives in a solvent such as toluene, and coating the mixture on the surface of a support such as a release liner. And cured to form a pressure sensitive adhesive layer made of the heat conductive composition of the present invention. At this time, if the surface of the pressure-sensitive adhesive layer is coated with a release-treated film having a different peeling force, the handleability is further improved. The preferable lower limit of the thickness of the pressure-sensitive adhesive layer is 10 μm, and the preferable upper limit is 200 μm.
m. If the thickness is less than 10 μm, sufficient adhesion may not be obtained and the thermal conductivity may decrease. When it exceeds 200 μm, the thermal conductivity is lowered and the cost becomes high. A more preferable lower limit is 30 μm, and a more preferable upper limit is 150 μm.
m.

As described above, the heat conductive composition of the present invention is used by being interposed between the heat generating element and the heat radiating element. The joint structure of the heat generating element and the heat radiating element, in which the heat conductive composition of the present invention is interposed between the heat generating element and the heat radiating element, is also one aspect of the present invention.

As described above, the thermally conductive composition of the present invention has sufficiently solved the problems of the prior art, and the thermal conductivity does not decrease due to thermal convection even when the heating element is operated. In addition, it has excellent adhesion and adhesiveness and can be used for joining heat-generating bodies such as electric and electronic parts to heat-dissipating bodies, and has excellent heat conductivity and adhesiveness, and is extremely easy to handle. A good heat conductive pressure sensitive adhesive sheet and the like can be provided.

[0022]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. (Example 1) 100 parts by weight of benzyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.), 0.01 parts by weight of n-dodecanethiol, and 90 parts by weight of ethyl acetate were placed in a separable flask equipped with a cooling tube, a thermometer and a stirrer, Under a nitrogen gas atmosphere, the temperature was raised to a temperature at which reflux occurred, and the temperature was maintained for 20 minutes. Then, a solution prepared by dissolving 0.2 parts by weight of benzoyl peroxide in 5 parts by weight of ethyl acetate was added dropwise and reacted for 4 hours, and then a solution of 0.1 parts by weight of benzoyl peroxide dissolved in 5 parts by weight of ethyl acetate was added. It was added dropwise and the reaction was continued for 4 hours. Then, add 50 parts by weight of toluene and stir to mix,
A polymer solution was obtained. The weight average molecular weight (Mw) of the obtained polymer was measured by gel permeation chromatography in terms of styrene and found to be 300,000. 50 parts by weight of dioctyl phthalate and aluminum nitride having a purity of 99% (trade name: Grade F, manufactured by Tokuyama Corporation) 100 parts by weight based on the solid content of the obtained polymer solution.
Parts by weight were added and mixed until uniform to obtain a heat conductive composition solution. The obtained thermally conductive composition solution was applied to a release-treated 50 μm-thick polyethylene terephthalate film surface so that the thickness after drying would be 100 μm.
It was dried at 0 ° C. for 1 hour and further dried under reduced pressure to obtain a heat conductive pressure sensitive adhesive sheet. The resulting heat-conductive pressure-sensitive adhesive sheet had excellent adhesion and adhesiveness as well as excellent heat conductivity.

Example 2 Benzyl methacrylate 10
Except that 100 parts by weight of dimethylaminoethyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) was used instead of 0 parts by weight and the amount of n-dodecanethiol was set to 0.02 parts by weight.
A polymer solution was obtained in the same manner as in Example 1. The Mw of the obtained polymer was 270,000. 40 parts by weight of isostearic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 99% pure boron nitride (trade name: Grade HGP, manufactured by Denki Kagaku Kogyo Co., Ltd.) based on 60 parts by weight in terms of solid content of the obtained polymer solution. ) 100
Parts by weight were added and mixed until uniform to obtain a heat conductive composition solution. A thermally conductive pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 using the obtained thermally conductive composition solution. The resulting heat-conductive pressure-sensitive adhesive sheet had excellent adhesion and adhesiveness as well as excellent heat conductivity.

[0024]

EFFECTS OF THE INVENTION According to the present invention, excellent thermal conductivity can be obtained without causing heat convection that significantly deteriorates thermal conductivity even when the heating element is in operation, while having excellent adhesion and adhesiveness. It is possible to provide a heat conductive composition having the same, a heat conductive pressure-sensitive adhesive sheet made of the heat conductive composition, and a joint structure of a heat generating element and a heat radiating body using the heat conductive composition.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 101/00 C09J 7/02 Z 5F036 C09J 7/02 11/00 11/00 201/00 201/00 H05K 7/20 F C09K 5/08 H01L 23/36 M H05K 7/20 C09K 5/00 D F Term (Reference) 4F100 AA13 AK01B AK25K AK42 AL05B AT00A BA02 DE01B GB41 JG01B JJ01B JJ06A JJ10 JL11 JL13B1061 0202BB01 CD001 CF001 CK021 CP021 DA077 DA097 DE107 DE147 DJ007 DK007 DM007 EA046 EH076 EH146 EN096 FD117 FD207 GQ00 4J004 AA07 AA08 AA09 AA10 AA11 AA13 AA14 AA15 AB03 CB03 CC02 FA05 4J040 DF001 ED001 HA066 HA206 HA296 HA326 HB03 HB22 HB30 JA09 JB09 KA03 LA08 PA23 5E322 AA01 AB06 FA06 5F036 AA01 BB21 BD13 BD21

Claims (6)

[Claims] 1. A heat conductive composition comprising two or more kinds of compounds, which is used by being interposed between a heating element and a heat radiating element, wherein the two or more kinds of compounds operate the heating element. It is in a mixed state that does not spontaneously separate at a temperature lower than the temperature range, and at the temperature within the operating temperature range of the heating element, it is phase-separated into what leaks and what does not leak. A heat conductive composition. 2. A compound containing at least one compound that is solid or semi-solid at a temperature within the operating temperature range of the heating element and at least one compound that is liquid at a temperature within the operating temperature range of the heating element. The heat conductive composition according to claim 1. 3. The heat conductive composition according to claim 2, wherein the compound which is solid or semi-solid at a temperature within the operating temperature range of the heating element is an adhesive resin. 4. The heat-conductive composition according to claim 1, which contains at least one kind of heat-conductive fine particles. 5. A heat-conductive pressure-sensitive adhesive sheet comprising the heat-conductive composition according to claim 1. 6. The method according to claim 1, wherein the heat generating element and the heat radiating element are provided between
A joint structure between a heat generating element and a heat radiating element, characterized in that the heat conductive composition according to 3, 4, or 5 is interposed.